Screw-thread-cutting tool.



4 Ross.- Q'scnnw T `CUTTING T0013. .QPHIOATION'HLED MA311, 190B'.

915,383. Patented Mar. 16, 1909.

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FRANK E. Ross, orciiireRrD-dn, MSSAoHusn'rTsi.

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Specification of Letters Patient. i

" Patente@ naiven 1e, 1909.

Application led March lil,v 1908. Serial No. 420,316,r

@ahorn 'it may concern: m itvlniown 'that` LFRAN'K E. Ross, of Bainbridge, county of' Middlesex, State of 'Mesaachusetta yhave invented an Improvement in Screw-ThreadCutting Tools, of tariflich 'the followin .is a specification.

"lffhiainvention re ates to sorew-thread cuttingto i for cutting external or internal .fiorewthreada and'has for its object to con- `struct a tool for simultaneously cutting one rangle of one thread and the opposite angle of 'another thread, or it may he the opposite angle of the same thread, so that as the tool travels along and the work revolves, both angles of the threads will be cut. Usually ne threadecutting tool travels over the work verai times before the threads are finished, .l during each excursion the cutting ofthe cada will be partially performed until iinally, when the cutting-tool has sunken venouglfi into the work, the threads will herorrned and finished.

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the preferred form of my invention thel tlnead-cutting ribs are arranged perimetricallly on a notched disk, in planes at right angles to the axis of the disk, and the end of the tool-holder bearing said disk is offset so that said dislrl is supported in a plane corresponding to the angle of the thread with relation to the axis of the bar on which the thread is formed.

The'inventin also has for its object to `provide improved means for rigidly securing the disk bearing the thread-cutting ribs to its holder.

Figure l is a side elevation of a screwthread cuttingtool embodying this invention. Figw 2 is a horizontal section of the saine taken on the dotted line 2 2 Fig. 1.l Fig. 3 is an end view of the tool. Fig. 4 is a side elevation of the bushing which is emy loyed in securing the diskto its holder. Jig. 5 is an enlarged detail showing my preferred form of angularly-forrned` thread-cutting ribs.` Fig. 6 is a rear side elevation of the disk.,` Fig. 7 is a sectional detail of a portion of the tool in engagement with the work.'l Fig. 8 is a sectional detail of a noodi-l ied form of tool to be described, and Figf 9 described.. y t

a represents. alllcircular disk having 011 vits perimeter twoter more angularly formed is another modified form of tool to he,

thread-cutting ribs, twoonly as a and a2, being herein. shown merely for the purpose of illustration. These ribs are arranged side by side in parallelism, and are suitably `spaced apart.' The disk is notched on its edge, one wall of said notch, as at a3, extendving `from the edge inward toward the center approximately radially and the other wall, as a4, extending from the-bottom of the aforesaid wall to the edge on a chord of the arc of the disk. The disk is adapted to be. rigidly secured to a holder .by means to be hereinafter described. The -angles of the outer sides of the angularly formed threadcutting ribs a', a2, correspond to the angles of the opposite sides or corresponding sides of the threads to be cut, and the angles ofthe inner sides thereof are formed at approximately right angles to the axis of the disk, or of the work, as represented in Fig. 7; but in lieu thereof the angles of the in ner sides ol' sai ribs may be formed at `angles corresponding to the angles of the op posite sides or corresponding sides of the threads to be cut and the angles of the outer sides thereof may be formed at `approximately right angles to the axis ofthe disk, or ofthe work, as shown in Fig. 8. The two ribs thus formed are oppositely disposed,` and will respectively act upon and out the opposite sides of the threads and during the cutting operation spaces will be provided between the unacted-upon sides of the threads. and the ribs for clearance. The ribs are spaced apart to `aotupon two separate threads, Vas for instance, in the form shown in Fig.l 7, which is'the preferred form of my invention, the angular y formed ribs will act upon or engage two threads which are located at o posite sides of a disengaged thread, or in otli alternately arranged threads, while in the form shown in Fig. 8, the angularly formed ribs while oppositely disposed will act upon or engage the opposite sides of the same thread.` The ',angularly'formed ribs act simultaneously, yet each performs its. own operation 'of' cutting one side ofthe thread, so that while one thread is being cut upon onel side, another thread or-it may be the same thread is being "out upon the oppositeV Side'. A Byjthe employment of two thread-cutting er words will act `upon the formed Wit askaisformeawaharecessalha ribs, arranged side by side so as'to act simultaneously, each having a single cutting face, there is no Wedging action produced as the threads enter the Work, ample clearance is provided for the chips, the cutting tool can e fed in l.straight toward the Work, using a simple cross slide; vand the usual end thrust on the Work and the usual side thrust on the tool is e ualized.

I prefer to make one of the angularly formed thread-cutting ribs longer than the other, as best shown in Fig. -5, whereiny the rib a2 is made longenthan the rib c', and in lsuch case the rib a acts upon the work in advance of the rib a2; also, as shown in said figure the end of the rib ais flattened and the end of the rib a2 is flattened and 'alsobeveled for a short distance on its straight side. By thus forming the ends of the ribs, spaces are formed between the threads on the work, but my invention is not limited vto any particular form which may be given to the ends of the ribs, as such formation will varyA according to the Work which is to be done.

Ordinarily in cutting'a thread the tool is moved lon itudinally with respect to the Work and t e Work is revolved with res ect to the tool, and when cutting thethrea by my process the tool and work will be moved in the usual manner. In cutting the thread the tool usually passes over the work several times, each time the an larly-formed threadcutting ribs sinking ee er into the Work, and it will be observed t at on the straight sides of the ribs ample space Vis always provided for clearance.

In the preferred form of my inventionV the thread-cutting ribs are arranged on the perimeter of the disk in planes atright angles to the axis of the disk, as shown in `Figs. 2 and 3, but in lieu thereof they may be arranged thereon spirally, as shown in Fig. 9. When arranged 1n lanes at right angles to the axis of the disk t e end ofthe tool-holder c is offset at a slight angle with respect to its shank, as shown in Figs. 2 and 3, s'o that theldisk is supported out of a true vertical plane and at an an le corresponding to the an levofthe threat? with respect to the axis oft e bar on which it is formed.l l. Y, 'As a means for rigidl securing the disk av to its holder c said dis is'provided' With a center-boleto receive 'a bolt c-.which extends through a tapered bushing c?, which is placed in a hole inthe holders, and projects'from the holder at botliisides.v 'The n ut -on the bolt is turned down ti htly against the outer projecting end -of sai 1 bushing'.- Theo posite or inner ijlirojectingjend vof the bus ,0

parallel sides, Aas represente arca, Fig. 4,' and the reanfCQ-fbrside of thle 'ara el sides, to receive the" parallel-jai e Aend of the bushing, which latter' is made to snugly fit it. The inner projecting end of the bushing serves as a key to engage and hold the disk from rotation and as the disk is ground away and thereby caused to occupy different relativepositions to its holder, the saidinner projecting end of the bushing may always properly enter the recess in the disk byreason of said bushing being permitted to turn in the. hole in the holder When loosened by loosening the nut on the bolt. The bushing therefore serves as an adjustable key for engaging the disk, being adapted to occupy any number of positions according to the requirements of the case, and in any position Whatsoever that it may be set it may berigidly secured to the holder. This manner `of securing the disk is simple and is easily operated, but so far as thisfeature of my invention is concerned any other means for securing the disk may be employed in lieu of that herein shown. v g

The straight sides of the angularly formed thread-cutting ribs are referably formed 'at a veryvslight angle to t e axis of the disk to increase the Width of the ribs at the base, and thereby correspondingly increase their 'strength' j One face of the disk is provided-With a series of marks, see Fig. 1', which 'are arranged tangential toa small circle concentric to the axis of the disk and said vmarks serve as gage lines to assistthe 0 )erator in grinding the Wall a3 of the notch`o the tool. Any number of marks may be provided. The vperimetrical thread-cutting ribs may also have a depth line mark formed on them to assist the operator in determining when j the .tool has entered the Work to the vproper de th.

. aving thus described my invention, what I claim as new and desire to secure by Letters Patent is l. A screw-tread cutting-tool having two thread-cutting'ribs, each having one cutting face onl saidribsbeing arranged side by side Wit their cutting faces op ositely disposed7 substantially as described). 5 f

2. In a screw-thread cutting-tool, ahr-Eder, la disk having a cent-er hole and having un its rear side a parallel sided recess, a bushing 'extending through a hole in the holder and projecting therefrom at each end, one end .of sai'dbushing being formed with parallel sides .Whichenters Vthe recess in the disk, and a bolt extending through said disk and bushing having thereon a nut which is adapted to be turned up against the outer end of the bush- I rear side a parallel sided recess, an adjustablev tapered .bushing extending through a hole in from the holder and is shaped to correspond "name to this speeioeton, in the presence of to. theshape of the reeess in thedsk, said two subscribing Witnesses. bushing engaging the disk in any position FRANK E. ROSS. 5 said disk may occupy relative to its holder, Witnesses: Vand means for holdln the parts assembled, B. J. NoYEs, sulstantialy es desried. H. B. DAVIS.

the holdef, thegner end ofwheh projects In testimony whereof, I have signed my 

